It is strange that fire accidents often happened at night and are usually going to cause power outage to the whole building. Not to mention that it only takes minutes for thick black smoke to fill a building. Therefore, if you wake up to a fire, it is more than likely that you are trapped in an entirely pitch-black environment which is going to cause troubles or even dangers to you while trying to escape from the burning building.
In most buildings, only at specific locations relation to designated escape routes leading to emergency exits, such as floor level exits or staircases, are required by current building safety regulation to have emergency lightings or escape signs for ensuring the lighting is provided promptly, automatically and for a suitable time in a specific area when the normal power supply to the normal lighting fails, as those shown in FIG. 1. However, there can be not enough emergency lightings or escape signs in the building to ensure that persons in the building can evacuate safely in an event of emergency since they are only being required by regulation to be installed in the building only at certain designated locations and exits. Moreover, those emergency lightings or escape signs can easily either be blocked by smoke form being seen by persons trapped in building since during a fire that it only takes minutes for thick black smoke to fill a building, or can be damaged by fire, so that they may not function as expected during emergency.
In addition, as those emergency lightings or escape signs are usually powered by battery, they are mostly likely to malfunction due to battery failure or insufficient power stored in the battery. Therefore, it is required to check or replace the batteries in those emergency lightings or escape signs in a regular basis which can be most troublesome.
There are already many studies relating to the aforesaid disadvantages. One of which is a technique of liquid driven generator for low power electrical component disclosed in TW Pat. No. I269850. The low power electrical component can be a light capable of being powered by a generator as the generator is designed to be driven to rotate by a fluid flow for generating electricity accordingly. Operationally, the generator can be installed in a fire-sprinkler so that when the fire-sprinkler is activated for discharging water, the generator can be driven to rotate and thus generate electricity for providing power to the light module that is also being installed in the fire-sprinkler. Since there can be an array of such fire-sprinklers being arranged on the ceilings of any building, they can provide sufficient illumination for persons trapped in the building when they are being activated by fire accident. Another such study is a water-power light disclosed in U.S. Pat. No. 4,616,298, that it is substantially an illumination device adapted for sprinkler systems for enabling the same to be powered by an axial generator with radial blades while the radial blades are driven to rotate by a flow of water in the sprinkler systems.
Please refer to FIG. 2, which is a schematic diagram showing how a flow of water is impinging by an angle upon a blade of a conventional water-powered generator. In FIG. 2, since the water flow 90 is moving linearly, the propelling force of the water flow 90 can not be fully received by the blade 91 for driving the same to rotate so that the electric-generating efficiency of the resulting generator is not satisfactory.